"loose fiber obtained from taking apart old hemp ropes," early 15c., from Old English acumba "tow, oakum, flax fibers separated by combing," literally "what is combed out," from Proto-Germanic *us-kambon (source of Old High German achambi); first element cognate with Old English a- "away, out, off;" second element from stem of cemban "to comb," from camb "a comb;" from PIE *gembh- "tooth, nail" (see comb (n.)).